Are Steroid sponsors legal?

In the past several weeks I've had people try to spam my yahoo group with cheap roids, grow your own pot and micro penny stocks.

Now I'm not too certain of the legality of these things because.

1. My group is obviously hosted in the US.
2. I'm not sure if I'm personally liable for stuff sent to my group.
3. I can't even begin to understand the yahoo T.O.S.

And I really don't want to lose my group because I use it for so much. People email me for underware, vids, etc.

So any help?

You know, i honestly dont know, might be one of those questions you need to ask your attorney :)

Regards,

Lee